Dinosaurs: a global perspective

In more recent times, this approach has been applied much more
broadly and in a much more ambitious way. Paul Upchurch of
University College London and Craig Hunn at Cambridge hoped to
explore the entire family tree of the Dinosauria for evidence of
similarities in patterns of stratigraphic ranges and cladistic
patterns by looking at large numbers of dinosaurs. These were
compared to the currently established distributions of the
continents at intervals through the entire Mesozoic Era. An
attempt was being made to find out whether an overall signal did
emerge that was suggestive of a tectonic influence on the
evolutionary history of all dinosaurs.

Despite the inevitable ‘noise’ in the system resulting largely from
the incompleteness of the fossil record of dinosaurs, it was
heartening to note that statistically significant coincident patterns
emerged within the Middle Jurassic, the Late Jurassic, and the
Early Cretaceous intervals. This indicates that tectonic events do, as
expected, play some role in determining where and when particular
groups of dinosaurs flourished. What is more, this effect has also
been preserved in the stratigraphic and geographic distributions of
other fossil organisms, so the evolutionary history of great swathes
of organisms was effected by tectonic events and the imprint is still
with us today. In a way, this is not new. I need only point to the
unusual distribution of marsupial mammals (found only in the
Americas and Australasia today), and the fact that distinct areas of
the modern world have their own characteristic fauna and flora.
What this new research suggests is that we may well be able to trace
the historical reasons for these distributions far more accurately
than we had supposed possible.